BIO 115 Lecture Notes - Lecture 16: Cough Reflex, Blood Gas Tension, Peripheral Chemoreceptors
Document Summary
Major respiratory afferent systems and the reflex responses they elicit. Slowly adapting pulm stretch receptors (psr) in airway smooth muscle, activated by lung inflation and/or bronchoconstriction. Breuer-hering reflex: when lung inflates 3x greater than normal. Vt, signals to stop inspiration and start expiration (i. e. exercise) Found between epithelial cells in airway, activated by irritants, rapid large inflation, or lung deflation. Facilitate augmented inspiration (sigh), expand alveoli, overcome atelectasis. Cause cough reflex, mucus production, and bronchoconstriction. Close to alveoli (edema-stimulated) or epithelium (irritant stimulated) Airway protective reflex - cause rapid, shallow breathing, dyspnea. Induce coughing (irritant below oropharynx) to clear airway. Activated by edema: left-heart failure, ild, pneumonia, pe. Simulated by low pao2, high paco2, and low ph. Once pao2 drops below 60 mmhg increased ventilation. Central: in the vrc, in the retrotrapezoid nucleus. Stimulated by high paco2 and low ph (not by changes in pao2!) More responsive to changes in paco2 than ph b/c h+ can"t cross the bbb.
